The use of polypeptides, including enzymes, in the circulatory system to obtain a particular physiological effect is well-known in the medical arts. Further, within the arts of industrial applications, such as laundry washing, textile bleaching, person care, contact lens cleaning, food and feed preparation enzymes are used as a functional ingredient. One of the important differences between pharmaceutical and industrial application is that for the latter type of applications (i.e. industrial applications) the polypeptides (often enzymes) are not intended to enter into the circulatory system of the body.
Certain polypeptides and enzymes have an unsatisfactory stability and may under certain circumstances--dependent on the way of challenge--cause an immune response, typically an IgG and/or IgE response.
It is today generally recognized that the stability of polypeptides is improved and the immune response is reduced when polypeptides, such as enzymes, are coupled to polymeric molecules. It is believed that the reduced immune response is a result of the shielding of (the) epitope(s) on the surface of the polypeptide responsible for the immune response leading to antibody formation by the coupled polymeric molecules.
Techniques for conjugating polymeric molecules to polypeptides are well-known in the art.
One of the first commercially suitable techniques was described back in the early 1970s and disclosed in e.g. U.S. Pat. No. 4,179,337. Said patent concerns non-immunogenic polypeptides, such as enzymes and peptide hormones coupled to polyethylene glycol (PEG) or polypropylene glycol (PPG). At least 15% of polypeptides' physiological activity is maintained.
GB patent no. 1,183,257 (Crook et al.) describes chemistry for conjugation of enzymes to polysaccharides via a triazine ring.
Further, techniques for maintaining of the enzymatic activity of enzyme-polymer conjugates are also known in the art.
WO 93/15189 (Veronese et al.) concerns a method for maintaining the activity in polyethylene glycol-modified proteolytic enzymes by linking the proteolytic enzyme to a macromolecularized inhibitor. The conjugates are intended for medical applications.
It has been found that the attachment of polymeric molecules to a polypeptide often has the effect of reducing the activity of the polypeptide by interfering with the interaction between the polypeptide and its substrate. EP 183 503 (Beecham Group PLC) discloses a development of the above concept by providing conjugates comprising pharmaceutically useful proteins linked to at least one water-soluble polymer by means of a reversible linking group.
EP 471,125 (Kanebo) discloses skin care products comprising a parent protease (Bacillus protease with the trade name Esperase.RTM.) coupled to polysaccharides through a triazine ring to improve the thermal and preservation stability. The coupling technique used is also described in the above mentioned GB patent no. 1,183,257 (Crook et al.).
JP 3083908 describes a skin cosmetic material which contains a transglutaminase from guinea pig liver modified with one or more water-soluble substances such as PEG, starch, cellulose etc. The modification is performed by activating the polymeric molecules and coupling them to the enzyme. The composition is stated to be mild to the skin.
However, it is not always possible to readily couple polymeric molecules to polypeptides and enzymes. Further, there is still a need for polypeptide-polymer conjugates with an even more reduced immunogenicity and/or allergenicity.